Abstract:
The present invention provides a method and apparatus for determining intensities and peak wavelengths of light. The apparatus comprises one or more pairs of sensing units for sensing the light, a first sensing unit of a pair configured to sense a first intensity of the light in a first predetermined wavelength range with a first predetermined spectral responsivity and a second sensing unit of a pair configured to sense a second intensity of the light in the first predetermined wavelength range with a second predetermined spectral responsivity. The apparatus further comprises a processing system operatively connected to the one or more pairs of sensing units; the processing system configured to determine the intensity and peak wavelength for each of the one or more predetermined wavelength ranges of the light according to one or more predetermined functional relationships between each of the first intensity and second intensity.
Abstract:
The present invention provides a method and apparatus for optical feedback control for a lighting unit (10), wherein the control signal for an array of one or more light sources (20) is configured using a CDMA modification signal. Signals provided by an optical sensor (60) at least detecting the light emitted by the array of one or more light sources, can be filtered based on the CDMA modification signal, thereby enabling discrimination of the portion of the signals from the optical sensor (60) which are reflective of optical characteristics of the light emitted by the array of one or more light sources (20). In embodiments of the present invention, the determined optical characteristics can be used for example for feedback control of an illumination system.
Abstract:
The present invention provides an illumination apparatus comprising one or more first light-emitting elements and one or more second light-emitting elements and a control system configured to control the operation of the one or more first and one or more second light-emitting elements. As the illumination apparatus according to the present invention is configured to generate utility illumination using two different and substantially monochromatic light-emitting element light sources, the light pollution resulting from the utility illumination generated by the illumination apparatus is reduced, when compared to a polychromatic light source.
Abstract:
The present invention provides a method and apparatus for controlling the activation of an electronic device. For a desired activation ratio, which defines the "ON" time relative to the "OFF" time of the electronic device fo r a given time period, the method and apparatus according to the present invention evaluates an activation sequence. The activation sequence comprise s two or more activation time periods and one or more deactivation periods, wherein the ratio between the two or more activation periods and the predetermined time period is equivalent to the desired activation ratio.
Abstract:
The present invention provides an extension to a standard N-bit digital pulse width control method which can discriminate 2N discrete pulse widths per pulse cycle. The present invention provides a method and apparatus that can modulate the pulse widths over a period of 2M pulse cycles in which each pulse cycle can have its own pulse width or respective duty cycle. The resulting time averaged or effective pulse width therefore can be controlled with a resolution of 2N+M states rather than a resolution of 2N states as is common with standard methods.
Abstract:
The present invention provides a light source having an improved output optical quality. In general, the light source comprises one or more light-emitting elements in each of at least a first, a second and a third colour. The combined spectral power distribution of these light-emitting elements generally defines a spectral concavity. The light source further comprises a light-excitable medium configured and disposed to absorb a portion of the light emitted by one or more of the light-emitting elements and emit light defined by a complementary spectral power distribution having a peak located within the concavity. By combining the spectral output of the light-emitting elements with the spectral output of the light-excitable medium, an optical quality of the light source is improved.
Abstract:
The present invention provides a method and apparatus for controlling the thermal stress in lighting devices, for example light-emitting elements, that are exposed to large thermal gradients typically upon start-up, for example light-emitting elements operating in relatively cold ambient environments. The present invention provides an apparatus that can reduce this thermal stress, wherein the apparatus comprises a temperature determination mechanism for evaluating the temperature of the light-emitting elements prior to activation, and a control system to control the drive current such that it is gradually ramped up to the desired steady state peak current value, wherein the ramping of the drive current is dependent on the evaluated temperature of the light-emitting element.
Abstract:
Disclosed are a method and apparatus for optical feedback control for a lighting unit (10) for generating light having a desired luminous flux and chromaticity. The control signals (110, 210) for the drive currents of each array of one or more light sources are independently configured using a suitable modification signal (111, 211) for each array. In this manner, upon detection of the output light of the arrays, which will have encoded therein a respective modification signal, a controller can be configured to separate each array's contribution based on the respective modification signal. The modification signal can be configured to modulate the pulse widths of drive currents supplied to each array.
Abstract:
Tristimulus colorimeter apparatus and methods of tristimulus colorimetry are described. The tristimulus colorimeter apparatus can be used for determining color of light by specifying a first, a second and a third tristimulus value for the light. The colorimeter apparatus may detect signals according to color matching functions having spectral responsivities matched by detectors of the colorimeters. The detected signals may be processed by one or more computations, such as matrix operations, to provide the tristimulus values of the color.